Hi Gaz01, there are a few jets available and the one i would suggest you try is the one i have circled. i believe it is a leaner jet and given yours is running rich it's worth a try. This particular jet normally comes out on the VE50 models. Replace the jet and read the plug for rich/lean condition after a couple of mows.
[Linked Image]
The other thing to note(and i'm not entirely positive about this)is the small bearing in the end of your jet is merely a "plug" to fill the hole after the jet was drilled from the factory. That jet appears to be off an earlier model as the later ones were cast solid on the front and all sizing was done from the other end.
Good luck.